Building the Expo Milano 2015, which opens on 1 May and has the theme ‘feeding the planet, energy for life’.
Photograph: Giuseppe Cacace/AFP/Getty Images

The launch on Friday of Expo 2015 – a world fair that is expected to draw 20 million people to Milan over the next six months – is heralded by some as a sign that Italy is finally back on its feet.

With just days to go, construction crews were still working around the clock in Italy’s fashion and business capital to get the site ready for its grand opening. But the verdict of Italy’s prime minister, Matteo Renzi – who came to power more than a year ago promising to shake the country out of its economic malaise – was, as ever, not short on confidence. “The Expo bet,” he declared, “has been won.”

If all goes according to plan – a phrase Italians tend to chuckle at – Milan will for 184 days play the perfect host to what is essentially an enormous but temporary theme park, with beautifully designed pavilions representing individual countries – the German and the UK pavilions will feature bees, Japan will offer up a “virtual meal” and Brazil has created a small tropical forest. All are built around this expo’s ecological theme: “Nutrire il Pianeta, Energia per la Vita (“feeding the planet, energy for life”).

But if expo is a symbol for Italy today, it is one that is full of contradictions.

When Milan won the right to host the event in 2008, beating the Turkish city of Izmir, it was hailed as a chance for the city to be “reborn”. Since then, the planning and execution of expo in an area about six miles from the city centre have been dogged by bureaucratic delays and corruption scandals that are an everyday reality for Italians.

Last year, seven people were arrested, including expo’s top procurement manager, as part of an alleged bid rigging investigation. At the time Milan’s mayor, Giuliano Pisapia, suggested that the possibility of wrongdoing was to be expected: “It is logical to anyone who knows the situation in our country.”

It did not end there. Earlier this year, the infrastructure minister, Maurizio Lupi - a member of the New Centre Right (NCD) party that is party of Renzi’s governing coalition – was forced to resign after he was allegedly caught up in a corruption scandal that touched several public contracts, including one for the Italian pavilion’s palazzo Italia (Italian palace). Lupi has not been charged with wrongdoing but had a relationship with a public works official who was arrested.

“What happened was mostly one year ago. After this, we put a lot of effort into not having other scandals again,” Giacomo Biraghi, an expo spokesman, told the Guardian.

When asked why it had been so difficult to keep the expo clean, given the international scrutiny the event was always going to be subject to, he adds: “I think the people involved thought that it was going to be like a normal public Italian work. But we found them.”

The job of weeding out corruption at expo has fallen almost exclusively on Raffaele Cantone, who was appointed to head Italy’s anti-corruption authority by Renzi last year.

The former mafia prosecutor recently said expo’s public contracts were “clean” but he is still asking questions, including about a contract between Eataly and expo, in which the internationally known Italian supermarket chain was awarded two communal restaurants within expo without having to bid for them. Eataly did not respond to an interview request.

Biraghi says the decision to offer the no-bid contract was taken because of Eataly’s unique global reputation and that the deal is now being “discussed” by Cantone and the head of expo, Giuseppe Sala. “The role of Cantone is exceptional; he is sort of double-checking everything,” Biraghi says.

If there was scepticism before Cantone’s arrival, those fears have largely been assuaged among Italy’s foreign partners. The US embassy says it believes the Italians pulled off a “feat”.

“Our impression is that the convictions and suspensions for corruption are actually signs that the system is working. It’s when you don’t have anyone arrested that you have to worry that corruption is out of control,” said one US official. “The Italian government took the corruption charges seriously and made credible efforts to cut it off.”

Even if the worst of the graft and corruption scandals are behind it, the looming issue for expo is whether the city is prepared for the event and whether it will have a lasting effect on a place that is often considered an afterthought for tourists who see Rome, Florence, and Venice, as Italy’s primary attractions.

“You can say, how is it possible to get it all done in one week’s time?” Biraghi says in an interview days before the 1 May opening. The corruption scandal, he acknowledges, slowed down construction work.

He denies speculation – the kind you hear in hotel lobbies and metro cars – that part of the Italian pavilion will be covered up until it is finished, around 5 May.

“We had two or three months of gasping,” he says. “But on the issue of timing – on ‘is it all ready?’ – I am very calm. Of course I would be calmer if we had five days more and ten days more.”

He points out that Milan and its skyline have been transformed since 2008. The city has expanded its metro service, doubled its “green space” and – somewhat ambitiously – plans to open ten new museums over the next two years.

Still, most Milanese are sceptical about the 1 May opening and fearful about security. On Wednesday police carried out pre-emptive raids on radical groups suspected of planning to disrupt expo’s launch, seizing fireworks, baseball bats, gas masks and material that could be used to make Molotov cocktails, AFP reported.

Libretti says she is doubtful that Milan itself will see too many benefits from the expo, given that the main attraction is relatively far away and she worries about the “bad impression” tourists will get from seeing African migrants at Milan’s main train station, a hub for immigrants as they make their way to northern European destinations.

Two Milanese men chatting on the sidewalk are not eager to speak with a reporter asking about the city’s readiness. “Is the city ready? No,” says one, with a laugh. “But it is very Italian to be ready in the last minute.”